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/* nbdkit
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <config.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include "internal.h"
#include "utils.h"
/* Detection of request to exit via signal. Most places in the code
* can just poll quit at opportune moments, while sockets.c needs a
* pipe-to-self through quit_fd in order to break a poll loop without
* a race.
*/
volatile int quit;
#ifndef WIN32
int quit_fd;
static int write_quit_fd;
#else
HANDLE quit_fd;
#endif
#ifndef WIN32
void
set_up_quit_pipe (void)
{
int fds[2];
#ifdef HAVE_PIPE2
if (pipe2 (fds, O_CLOEXEC) < 0) {
perror ("pipe2");
exit (EXIT_FAILURE);
}
#else
/* This is called early enough that no other thread will be
* fork()ing while we create this; but we must set CLOEXEC so that
* the fds don't leak into children.
*/
if (pipe (fds) < 0) {
perror ("pipe");
exit (EXIT_FAILURE);
}
if (set_cloexec (fds[0]) == -1 ||
set_cloexec (fds[1]) == -1) {
perror ("fcntl");
exit (EXIT_FAILURE);
}
#endif
quit_fd = fds[0];
write_quit_fd = fds[1];
}
void
close_quit_pipe (void)
{
close (quit_fd);
close (write_quit_fd);
}
/* The pragma here is for the write() call in set_quit below. RHEL
* 6-era gcc requires pragmas outside the function scope.
*/
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-result"
/* This function is called from signal handlers and MUST NOT do
* anything asynch-signal unsafe (malloc, printf, debug etc.) as that
* can be turned into an RCE. Example:
* https://www.qualys.com/2024/07/01/cve-2024-6387/regresshion.txt
* See also: signal-safety(7)
*/
static void
set_quit (void)
{
char c = 0;
quit = 1;
write (write_quit_fd, &c, 1);
}
#pragma GCC diagnostic pop
#else /* WIN32 */
/* Pipes don't work well with WaitForMultipleObjectsEx in Windows. In
* any case, an Event is a better match with what we are trying to do
* here.
*/
void
set_up_quit_pipe (void)
{
quit_fd = CreateEvent (NULL, FALSE, FALSE, NULL);
}
void
close_quit_pipe (void)
{
CloseHandle (quit_fd);
}
void
set_quit (void)
{
quit = 1;
SetEvent (quit_fd);
}
#endif /* WIN32 */
void
handle_quit (int sig)
{
set_quit ();
}
NBDKIT_DLL_PUBLIC void
nbdkit_shutdown (void)
{
set_quit ();
}
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